def main():
    import sys
    input = sys.stdin.read().split()
    ptr = 0
    N = int(input[ptr])
    ptr += 1
    A = []
    for _ in range(N):
        A.append(input[ptr])
        ptr += 1
    M = int(input[ptr])
    ptr += 1
    B = []
    for _ in range(M):
        B.append(input[ptr])
        ptr += 1

    all_fragments = A + B

    next_char = {}
    prev_char = {}

    # Process all fragments to build next and prev
    for frag in all_fragments:
        for i in range(len(frag) - 1):
            c = frag[i]
            d = frag[i + 1]
            # Check next conflict
            if c in next_char and next_char[c] != d:
                print(-1)
                return
            # Check prev conflict
            if d in prev_char and prev_char[d] != c:
                print(-1)
                return
            next_char[c] = d
            prev_char[d] = c

    chars = set()
    for frag in all_fragments:
        for c in frag:
            chars.add(c)
    chars = list(chars)
    total_chars = len(chars)

    # Find start nodes (no prev)
    start_nodes = []
    for c in chars:
        if c not in prev_char or prev_char[c] is None:
            start_nodes.append(c)

    # Check cycles and build chains
    visited = set()
    chains = []
    for s in start_nodes:
        if s in visited:
            continue
        current = s
        chain = []
        while True:
            if current in visited:
                # Cycle detected
                print(-1)
                return
            chain.append(current)
            visited.add(current)
            if current not in next_char:
                break
            current = next_char[current]
        chains.append(chain)

    # Check if all characters are visited
    if len(visited) != total_chars:
        print(-1)
        return

    if len(chains) != 1:
        print(-1)
        return

    # Combine the chain into the candidate string
    candidate = ''.join(chains[0])

    # Verify that all fragments are present as substrings
    # This is technically redundant but included for safety
    for frag in all_fragments:
        f = ''.join(frag)
        if f not in candidate:
            print(-1)
            return

    print(candidate)

if __name__ == "__main__":
    main()